It is known that it is possible to suppress a sudden change in an inertial force applied to a vehicle or a passenger, or to obtain a strong cornering force using the load shift of the vehicle by controlling a longitudinal acceleration of the vehicle according to a steering operation of the vehicle (for example, refer to NPL 1).
A basic concept of this control is expressed as Formula (1) that represents a target value of a longitudinal acceleration according to a lateral acceleration and jerk (differential value of acceleration).
                    [                  Expression          ⁢                                          ⁢          1                ]                                                                      G          xc                =                                            -                              sgn                ⁡                                  (                                                            G                      y                                        ·                                          G                      y                      †                                                        )                                                      ⁢                                          C                xy                                            1                +                Ts                                      ⁢                                                        G                y                ′                                                            +                      G            x_DC                                              (        1        )            
Here, Gxc represents a target acceleration in a traveling direction (vehicle longitudinal acceleration) of a vehicle, which represents a control variable of the vehicle. Gy represents a vehicle lateral acceleration, G′y represents a vehicle lateral jerk (differential of acceleration), sgn represents a function that returns a positive or negative signs of the value, Cxy represents a gain constant, T represents a time constant, and Gx—DC represents a bias constant. The respective constants vary depending on a vehicle type such as a mass, center of gravity and length of a vehicle, and also vary depending on the amount of control adjustment (so-called tuning).
In a case where a control in the traveling direction of the vehicle is performed according to Formula (1), if a resultant acceleration of a longitudinal acceleration and a lateral acceleration applied to the vehicle is shown in a diagram in which the transverse axis represents the lateral acceleration Gy and the longitudinal axis represents the longitudinal acceleration Gx, the transition thereof with time forms a curve. The curved transition indicates that a sudden change in an inertial force is small and also there is no uncomfortable ride and unnecessary acceleration and deceleration. In this way, this control appropriately controls the resultant acceleration, and is thus referred to as a “G-Vectoring control”.
However, the G-Vectoring control mainly relates to a vehicle control in a normal driving state of a vehicle, that is, in a state where a steering operation of the vehicle is effective without skid, and covers almost all situations during driving of the vehicle. Thus, even a small amount of time delay or control variable error that occurs in control may give unnecessary acceleration to a driver or a passenger, to thereby cause an uncomfortable ride.
In this regard, PTL 1 discloses a technique in which jerk is estimated from a vehicle state to detect the jerk with a less delay and a small error.
On the other hand, a control for suppressing an abnormal state, that is, skid of a vehicle, is referred to as a Vehicle Dynamics Control (VDC) or an Electric Stability Control (ESC).
In the VDC control, for example, a longitudinal acceleration and a lateral acceleration of a vehicle and angular velocity with respect to a running plane of the vehicle (yaw rate) are constantly measured, an error between a lateral acceleration obtained from a running velocity v and an angular velocity r of the vehicle and the acceleration obtained by a sensor is calculated to detect a skid state, and a decelerating force is given in a direction where the error is reduced, to thereby stabilize the vehicle.
Since the G-Vectoring control mainly relates to the normal state control and the VDC control mainly relates to the abnormal state control, both the controls may be mounted together on the vehicle.